From Nature:
What do you do for a living?
I’m an applied mathematician, but I work in a computer science lab [at Dartmouth College in New Hampshire]. My primary research area is developing computational and mathematical techniques to detect tampering in digital media. Most of my funding comes from law enforcement: I have a grant from the FBI. As well as doing research, I am often approached by people and organizations to help to authenticate digital media — so I’ve become something of a digital detective.
How’s business?
I get so many requests that I’ve had to start charging for my time. This dissuades many people, but many enlist my help. I’ve worked on an amazing array of cases — a prisoner had me analyse images of a crime scene, a man accused of adultery had me analyse images purportedly showing him with another woman, a doctor had me analyse images of a patient who claimed that the images had been doctored to cover up botched work. The list goes on and on. I also do quite a bit of expert-witness testimony.
More here.